What actually is "networking"?

I have plenty of friendships and connections I've had the pleasure of making in the professional world that I have done my best to cultivate. But I don't understand what "networking" means when people describe it as integral to getting a first-round interview at a firm.

I go to a decently elite college with plenty of alums at analyst/associate level positions at good firms. Is tracking down an email account of someone I have nothing in common with beyond alma mater and trying to get on the phone / zoom call so they can possibly ask for me to be boosted up to getting an interview actually a good use of my time?